v0.15.0: multipass CopyOptions, auto-detect sweep vs patch, speed control on damage zone entry/exit

- CopyOptions: replace resume/skip_on_error/batch_sectors with single multipass bool
- Disc::copy() auto-detects pass from mapfile state: no mapfile or NonTried → sweep, only NonTrimmed/Unreadable → patch
- Fix bug where mapfile with NonTried regions incorrectly dispatched to patch mode
- SectorReader::set_speed() default method, Drive impl sends SET CD SPEED
- On damage zone entry: set_speed(0x0000) for better error recovery
- On damage zone exit (50 consecutive good): set_speed(0xFFFF) to restore max speed
- Disc::mapfile_for() returns /tmp/<name>.mapfile for null:// output
- patch_internal/sweep_internal as private helpers, CopyResult gains recovered_this_pass

src/drive/mod.rs

@@ -599,6 +599,10 @@ impl SectorReader for Drive {
     ) -> Result<usize> {
         self.read(lba, count, buf, recovery)
     }
+
+    fn set_speed(&mut self, kbs: u16) {
+        Drive::set_speed(self, kbs);
+    }
 }
 
 /// Find the first optical drive on this system and open it.